Colwell won the 1974 Masters. He went on to win two titles at the USBC Open Championships, including the 1976 Classic doubles with Don Johnson and the 1977 team with Columbia 300. He also won eight PBA titles from 1972-76 including the 1976 PBA National Championship. He was runner-up in the 1979 Classic singles and enjoyed eight other top 20 finishes, all in the old Classic division.